More street drugs being laced with animal tranquilizer xylazine, Health Canada says

Health Canada says it's receiving an increasing number of illegal drug samples that contain xylazine — a veterinary sedative, relaxant and pain reliever not approved for human use.

According to a report from the federal agency, the animal tranquilizer began emerging as an additive to opioids and cocaine in 2019 and is most commonly mixed with fentanyl. Normally prescribed for dogs, cats, horses and cattle, xylazine can act as a depressant to the central nervous and respiratory systems.

"It can cause an unsafe drop in blood pressure and heart rate, and when taken with other depressants like opioids, increases your risk of overdose," said Samuel Tobias, a PhD student at the B.C. Centre for Substance Use.

The Health Canada report compiled illicit drug samples submitted by law enforcement agencies across the country to the agency's Drug Analysis Service (DAS).  The health agency says the data may not be completely representative of drug seizures and substances in the market.

Canada-wide, the data show the number of xylazine identifications jumped from 205 in 2019 to 2,324 in 2022.

B.C. makes up 21.2 percent of those samples, and saw the number of samples with xylazine quadruple from 58 in 2019 to 260 in 2022. In four years, a total of 487 samples were tainted with xylazine.

In a statement to CBC, Health Canada said xylazine has "also been detected in a proportion of opioid-related deaths."

Health Canada points out that overdose reversal drugs like naloxone are less effective on those who have consumed xylazine.

Tobias explained that xylazine is not an opioid, meaning naloxone — an opioid antagonist — is not able to counter it.

"If someone has consumed a lot of xylazine that's causing them to be in a lowered state of consciousness, using naloxone isn't going to wake them up," said Tobias.

Benzodiazepines more commonly tainting B.C. drugs

Tobias says xylazine is not nearly as common as other fentanyl additives like benzodiazepines, making up less than five percent of opioid samples submitted for drug checking.

"The prevalence of xylazine in samples has increased slightly over the past year and we've been seeing more of it within the last three months, but it's still always below five per cent of samples checked," said Tobias.

Still, Tobias cautions against consuming the drug because of possible extreme side effects and increased risk of overdose.

Alongside drops in blood pressure and slowed heart rate, Tobias also cites significant tissue damage, blackouts and memory loss.

"The sores [from damaged tissue] are large, and if deep enough, can sometimes lead to the requirement for legs to be amputated," said Tobias.

Tobias says extreme side effects have mainly been seen in places like Philadelphia and Puerto Rico, where xylazine is more common.

Tobias says the unpredictability of the unregulated drug supply can be deadly and advises having any illicit drugs tested.

"For people who rely on an unregulated drug supply, drug-checking services are one of the ways that people can find out what's in their supply before they consume it," said Tobias.